Tailoring of energy levels in (2Z)-2-cyano-2-[2-[(E)-2-[2-[(E)-2-(p-tolyl)vinyl]thieno[3,2-b]thiophen-5-yl]vinyl]pyran-4-ylidene]acetic acid derivatives via conjugate bridge and fluorination of acceptor u

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• 作者：Banjo Semire ; Abel Kolawole Oyebamiji…
• 关键词：Photovoltaic cell ; D–π–A dye sensitizer ; Electronic properties ; DFT
• 刊名：Research on Chemical Intermediates
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：43
• 期：3
• 页码：1863-1879
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Catalysis; Physical Chemistry; Inorganic Chemistry;
• 出版者：Springer Netherlands
• ISSN：1568-5675
• 卷排序：43

文摘

Density functional theory (DFT) was employed to investigate the role of fused thiophene and bridged thiophene π-linkers as well as acceptor unit fluorination in modifying the properties of dye sensitizers for dye-sensitized solar cells (DSSCs). A series of novel (2Z)-2-cyano-2-[2-[(E)-2-[2-[(E)-2-(p-tolyl)vinyl]thieno[3,2-b]thiophen-5-yl]vinyl]pyran-4-ylidene]acetic acid derivatives were simulated using DFT and time-dependent density functional theory to calculate their electronic and optical properties, population analysis, global reactivity index and light harvesting efficiency. The results showed that dyes with bridged thiophene π-linker have narrower energy bandgap (E_g) and longer absorption wavelength (λ_max) than those with fused thiophene π-linker. Also, fluorination of the acceptor unit of the dyes enhanced the electron accepting ability of 2-cyano-2-pyran-4-ylidene-acetic acid by lowering the lowest unoccupied molecular orbital (LUMO) energy, which leads to lower E_g, lower chemical hardness (η), and longer wavelength. Therefore, incorporation of fluorine atoms at the acceptor unit makes the conduction-band potential more favorable, leading to effective charge separation and charge transfer between donor and acceptor.